The present invention relates to operation completion detection means for vending systems, especially for vending systems that include a plurality of individually actuatable vend delivery motors for vending a variety of different products.
Many existing vending systems have been designed to utilize controllably actuatable motors or other actuators to effect certain operations. By way of example, vend delivery motors may be employed to effect the vending under appropriate conditions of a product or products selected by a customer, coin payout motors may be employed to effect distribution of overdeposited credit amounts back to a customer, and other motors may be employed for other purposes related to the vending system operation, such as movement of a cup into which a liquid is to be dispensed into position or the controlled opening and closing of a dispensing valve. Vending systems that utilize such controllably actuatable motors generally require that each motor, when controllably actuated, thereafter remain energized to operate for some sufficiently long enough period that the particular operation associated therewith will be completed as a result of such motor operation. Such period may be referred to as an operation cycle. In most cases, the operation cycle is functionally related to the operation of the motor and can be readily determined by monitoring the shaft rotation of the motor during the period of motor energization. As a result, it has been found that, by monitoring the shaft rotation of the selected motor, it is possible to determine when the motor has operated sufficiently under normal circumstances to cause the particular operation associated therewith to be completed and to permit the motor to be de-energized.
Typically, during an operation cycle of a vend delivery motor a variety of different events must occur in proper sequence for a product delivery to occur. Such events often involve several mechanical movements, all or most of which are controlled either directly or indirectly by operation of the appropriate vend delivery motor. In many instances, mechanical or electromechanical devices, such as cams and cam operated switches, are mounted upon or are associated with the output shaft of such motor to effect such events in their proper sequence. However, as a consequence thereof, it is important that the motor be in a proper initial state at the time it is first actuated to ensure that the desired sequence of operations will actually occur in the proper sequence, especially since the mechanical movements of a vend delivery operation are often interdependent to some extent. In many instances, if a particular mechanical movement required in a vend delivery operation is not performed, subsequent mechanical movements in a sequence of operation may not be effective to cause a product to be delivered. Consequently, it is recognized that the de-energization of a vend delivery motor must generally be effected at such a time and in such a manner at the conclusion of a delivery cycle so that such motor will be in a proper initial state for a subsequent vend delivery operation.
It is well known that a cam on the output shaft of a motor may be utilized not only to control the various mechanical movements necessary to effect a particular operation, such as to provide a product to the customer, but also to provide indications that the ouput shaft of the motor has rotated to such an extent that normal product delivery should have occurred and/or that the motor is in a proper state such that de-energization of the motor will leave it in a proper initial state for subsequent vend operations. As has long been recognized, a motor can therefore be provided with a cam on its output shaft, which cam may control the position of a cam operated switch that is wired in a circuit that is operatively connected to or monitored by the vend control means of the vending system.
Many known vending systems have made use of such types of circuits wherein cam operated switches form no part of the motor driving circuit but are disposed in separate sensing circuits wherein their operation is detectable by the vend control means of the vending system to effect other operations related to the vending operation and/or to cause the motor driving such cam to be de-energized. For example, U.S. Pat. Nos. 3,307,671; 3,508,636; 3,589,492; 3,687,255; 4,008,792; and 4,105,867, all of which are assigned to a subsidiary of Applicant's assignee, all disclose the use of a coin payout motor which has a cam operated switch associated therewith that is operable to effect a change in status of a separate sensing circuit, which change in status is detectable by the vend control means of the vending system and provides an indication thereto that the payout motor has operated sufficiently such that further operations relative to coin payback operations should be taken. In addition, U.S. Pat. Nos. 3,894,220 and 4,008,972, both of which are likewise assigned to the same subsidiary of Applicant's assignee, disclose the use of cam operated switches associated with vend motors to effect changes in status of separate sensing circuits, which changes in status are detectable by the vend control means of the vending systems to effect de-energization of the vend motors under appropriate conditions.
It will be appreciated that, as the number of individually selectable and actuatable motors for performing a given type of operation increases, so does the number of cam operated switches associated therewith. Quite obviously, if a separate sensing circuit were utilized for each cam operated switch, a large amount of replicative circuitry would be required for vending systems that employ a plurality of vend motors, especially for certain vending systems that now employ thirty or sixty or even more vend motors. To avoid the necessity of providing such replicative circuitry, many known systems that employ a plurality of vend motors, such as those disclosed in U.S. Pat. Nos. 3,894,220 and 4,008,972, use a daisy chain wiring technique with the plurality of cam operated switches. While such types of arrangements have generally been found to achieve desired results, they do have certain disadvantages associated with them, as well. A separate sensing circuit, with all the wiring attendant thereto, is still required for such systems, and, because of the daisy chaining required, the failure of a single motor, such as by hanging up partway through its operation cycle, may be sufficient in some circumstances to totally disable the sensing circuit and to thereby render the entire vending system inoperable.
Other known systems have also been developed wherein the cam operated switches associated with the particular motors have been so utilized that, when the movable switch contact of the cam operated switch means associated with a given motor is in one position, such cam operated switch comprises a portion of a motor hold circuit to ensure that, under certain conditions, once motor operation has been initiated by some means, motor energization will be continued for some period of time as determined by the controlled switching action of the associated cam operated switch. For example, U.S. Pat. No. 3,307,671 discloses the use of a cam operated switch associated with a refund motor in a motor hold circuit for such motor, the purpose of which is to enable the motor to complete an operating cycle and stop at a predetermined position. As the number of motors increases in a vending system, however, so does the amount of replicative circuitry required to provide motor hold circuitry for each motor. U.S. Pat. No. 4,034,839, assigned to a subsidiary of Applicant's assignee, discloses one vending system in which a plurality of cam operated switches are employed in a daisy chain arrangement in motor hold circuitry to ensure that a given motor will remain energized to complete an operation even if the motor selection switch which was required to be actuated to initiate motor energization is de-actuated prior to completion of motor operation. U.S. Pat. No. 4,478,353, assigned to the same subsidiary of Applicant's assignee, discloses a different system in which cam operated switches are employed with sold out switches associated with the vend motors to establish motor hold circuits to maintain energization of a given motor so that it can complete its operation cycle even if the product being vended is the last product and its delivery would normally cause a transfer of a sold out switch to prevent motor energization. U.S. Pat. No. 4,526,263, also assigned to the same subsidiary of Applicant's assignee, discloses a system in which a plurality of cam operated switches are so connected that the movable contact of each such switch in one position comprises a portion of a motor hold circuit for the motor with which it is associated and in another position comprises a portion of a separate sensing circuit similar in many respects to the types disclosed in U.S. Pat. Nos. 3,894,220 and 4,008,792.
To avoid the disadvantages associated with large amounts of replicative circuitry and/or daisy chaining arrangements of the cam operated switches, other systems have been developed wherein a cam operated switch associated with a given motor is connected in a series circuit with an impedance element, such as a resistor or capacitor, across, i.e., in parallel circuit with, such given motor. U.S. Pat. No. 4,458,187 discloses various embodiments of such types of systems. While such types of systems avoid some of the disadvantages attendant to daisy chain arrangements of cam operated switches and limit to some extent the amount of replicative circuitry that is required when a plurality of motors and associated cam operated switches are employed, because of the parallel circuitry asssociated with each motor, they still require fairly substantial numbers of the various components that are included in the circuit portions parallel to each of the motors and they may also require greater power, especially upon initialization of energization, to drive the selected motor than would be the case if such replicative circuitry for each motor were not present or required. Furthermore, with some types of such systems that include such parallel circuitry and employ AC signals to sense the status of the motors, several of which are disclosed in U.S. Pat. No. 4,458,187, additional circuitry, with the consequent additional costs that are associated therewith, may be required. By way of example, with some of the known embodiments that employ AC signals for sensing motor status, additional AC oscillators and band pass filters are required in addition to a plurality of capacitors for connection in series circuit with the cam operated switches across the motors and a relatively sophisticated detection circuit.